Crump Posted February 24, 2014 Posted February 24, 2014 (edited) Here is the inner gear door locks. When hydraulic pressure is released, the locks open. Edited February 24, 2014 by Crump
Sternjaeger Posted February 24, 2014 Posted February 24, 2014 Here is the inner gear door locks. When hydraulic pressure is released, the locks open. P51 inner gear door locks.jpg I'm afraid you are misinterpreting what's written there. I'm double checking with our engineer, but I'm pretty sure about my earlier assertion.
MiloMorai Posted February 24, 2014 Posted February 24, 2014 I did not say it did not have a clutch.....I said it is not unclutched when the motor is shut down. Two different things.....chuter. What do think automatic clutch effect means, mechanic? How do you think centrifugal clutches work?
Sternjaeger Posted February 24, 2014 Posted February 24, 2014 How do you think centrifugal clutches work? give him the time to find some random reference on the topic, then he'll lecture you with it
MiloMorai Posted February 24, 2014 Posted February 24, 2014 Boom Fairing door latch cable? What will happen on a P-51 is the inner gear doors will drop even if the uplocks are not damaged and manage to hold. You still sure he was talking about the main gear locks?
Crump Posted February 24, 2014 Posted February 24, 2014 Boom Fairing door latch cable? Right and notice it requires hydraulic pressure. The inner gear door system is latched whenever the doors are closed. Those latches are engaged when the gear is lowered and the inner doors close. When the hydraulic pressure is bleeds down after engine shut down, the doors drop down with the lack of hydraulic pressure. It is just a fact and quirk of the Mustangs gear system. Lose hydraulic pressure and the inner gear doors will deploy despite the lock. Up locks are not as solid as many readers seem to want to believe. It is one of the engineering hurdles that make complex unlimited aerobatic aircraft designs such a rarity. The pilot is not controlling the inner gear doors in the film. The doors closing is due to the hydraulic system pressurizing upon engine start. When the engine shut down, the doors were closed. The inner doors only open when the gear is in transition. The only other time they open is when you lose hydraulic pressure.
Sternjaeger Posted February 24, 2014 Posted February 24, 2014 Crump, since you're so sure of your assertion, can you show me the P-51 landing gear hydraulic diagram?
Sternjaeger Posted February 24, 2014 Posted February 24, 2014 (edited) Crump, here look a this no sign of hydraulic up-locks. And below is my exchange of text messages with our man after I asked him the question: Him: "the clam doors have mechanical manual up-locks operated by the gear lever but are also held shut by the hydraulic actuator ram, if you loose pressure then the up locks hold them shut to get the gear down you select gear down which should release doors if not there is a secondary system which is operated by the hydraulic pressure dump valve handle, the gear should by its own weight fall to lock position when no pressure in the system". Me: "That’s what I remembered, so the up-locks of the doors are NOT hydraulic, but just mechanical, and in order to release them you need to actuate the gear lever in the cockpit." Him: "Correct. Besides it would be a stupid system, what's the point of having a lock depending on the same circuit of the landing gear?" Edited February 24, 2014 by Sternjaeger
GOAT-ACEOFACES Posted February 24, 2014 Posted February 24, 2014 "Correct. Besides it would be a stupid system, what's the point of having a lock depending on the same circuit of the landing gear?" Thanks for the info from that P51 mech! It is nice to hear from someone who has actually turned a wrench on a P51 and not just a towel!
Crump Posted February 24, 2014 Posted February 24, 2014 Please go ask anyone who owns or flies a Mustang. It is just a fact and quirk of the Mustangs gear system. Lose hydraulic pressure and the inner gear doors will deploy despite the lock. Up locks are not as solid as many readers seem to want to believe. It is one of the engineering hurdles that make complex unlimited aerobatic aircraft designs such a rarity. One more time so it is clear.......the inner doors will deploy despite the lock.
Crump Posted February 24, 2014 Posted February 24, 2014 no sign of hydraulic up-locks This is why I mostly ignore you. You are not on the same subject. We are talking about the inner gear doors not the main uplocks. What do think happens when the fairing door operating valve and fairing door operating strut lose hydraulic pressure? Don't answer, it is already a fact and known quirk of the aircraft to those who operate one. The answer is the fairing doors open and do not close until the system is pressurized. http://www.google.com/imgres?client=safari&sa=X&hl=en&biw=1024&bih=671&tbm=isch&tbnid=_t0vqQ5MugZkPM:&imgrefurl=http://simple.wikipedia.org/wiki/North_American_Aviation_P-51_Mustang&docid=GWCXOmTcNIvfDM&imgurl=http://upload.wikimedia.org/wikipedia/commons/9/95/P-51_Mustang_01.jpg&w=3264&h=2448&ei=u44LU5CjF-qmyQH1-YCoDw&zoom=1&ved=0CGMQhBwwEg http://www.google.com/imgres?client=safari&sa=X&hl=en&biw=1024&bih=671&tbm=isch&tbnid=z7OZK89JKG6wvM:&imgrefurl=http://www.nationalmuseum.af.mil/factsheets/factsheet.asp%3Fid%3D513&docid=D5ecq4bw4p72UM&imgurl=http://www.nationalmuseum.af.mil/shared/media/photodb/photos/071024-F-1234S-008.jpg&w=1800&h=1197&ei=u44LU5CjF-qmyQH1-YCoDw&zoom=1&ved=0CEEQhBwwAQ http://www.google.com/imgres?client=safari&sa=X&hl=en&biw=1024&bih=671&tbm=isch&tbnid=ULbOwZMeDzEDWM:&imgrefurl=http://en.wikipedia.org/wiki/North_American_P-51_Mustang&docid=k_ItVZogJysCrM&itg=1&imgurl=http://upload.wikimedia.org/wikipedia/commons/5/54/P-51_of_the_Republic_of_China_Air_Force,_1953.jpg&w=605&h=415&ei=u44LU5CjF-qmyQH1-YCoDw&zoom=1&ved=0CJgBEIQcMCY http://www.google.com/imgres?client=safari&sa=X&hl=en&biw=1024&bih=671&tbm=isch&tbnid=15mCmLvl9YgabM:&imgrefurl=http://www.warbirdalley.com/p51pic.htm&docid=BQHFCRGmbIW8KM&imgurl=http://www.warbirdalley.com/images/P51-Mustang%252520Roush.jpg&w=532&h=353&ei=u44LU5CjF-qmyQH1-YCoDw&zoom=1&ved=0CLQBEIQcMDQ http://www.google.com/imgres?start=100&client=safari&sa=X&hl=en&biw=1024&bih=671&tbm=isch&tbnid=xEi5eDJG9tW4oM:&imgrefurl=http://dc.about.com/od/specialeventphotos1/ss/Military-Aircraft_10.htm&docid=JZXr5NeKyrLSSM&imgurl=http://0.tqn.com/d/dc/1/0/b/n/1/P-51_Mustang.jpg&w=1024&h=678&ei=K48LU7-6MMa9yAHW9YCgBQ&zoom=1&ved=0CCsQhBwwEThk http://upload.wikimedia.org/wikipedia/commons/e/ed/P-51_Mustang_Scat_VII_11.JPG http://www.google.com/imgres?start=100&client=safari&sa=X&hl=en&biw=1024&bih=671&tbm=isch&tbnid=4yEDGxRO_U4IOM:&imgrefurl=http://blog.airshowreview.com/2010-07-18/merlin-magic-the-p-51-mustang/&docid=RWBlS0K3HVl-xM&imgurl=http://blog.airshowreview.com/wp-content/uploads/2010/07/POF10-PS-D2_P-51_Mustangs_8208.jpg&w=1000&h=667&ei=l48LU8WCJKTuyAHd8YD4BA&zoom=1&ved=0CE8QhBwwIzhk Every picture you see if a Mustang with the inner doors down has suffered from this quirk of the design.
GOAT-ACEOFACES Posted February 24, 2014 Posted February 24, 2014 I beg to differ.. Note where it says, after the landing gear handle is placed at DN to RELEASE the gear uploacks. Hope this helps! 1
69th_chuter Posted February 24, 2014 Posted February 24, 2014 Your case is based entirely on aircraft with the gear DOWN and is accurate, for the gear DOWN condition. BUT. The uplocks for both the gear and clamshells are only engaged with the gear handle in the UP position because the cables running from the gear handle bellcrank has them released when the gear handle is in the gear DOWN position. Therefore, when the handle is down the only thing holding the clamshells closed is hydraulic pressure. When the gear (and gear handle) is in the UP postion both the gear and clamshells are held by the uplocks. And I'm not really sure if you actually want me to explain a centrifugal clutch ... { Hi, Stern }
Sternjaeger Posted February 24, 2014 Posted February 24, 2014 Please go ask anyone who owns or flies a Mustang. It is just a fact and quirk of the Mustangs gear system. Lose hydraulic pressure and the inner gear doors will deploy despite the lock. Up locks are not as solid as many readers seem to want to believe. It is one of the engineering hurdles that make complex unlimited aerobatic aircraft designs such a rarity. One more time so it is clear.......the inner doors will deploy despite the lock. I did, someone that owns and maintains Mustangs. I will go through the procedure again, perhaps this will help: The landing gear on the P-51 is hydraulically actuated, and so are the clam doors and tailwheel. They all respond to the same hydraulic system, as specified in the diagram posted above. In order to ensure that the gear doors stay up and to avoid them opening in case of hydraulic pressure loss, there are mechanical locks that keep the doors shut when the landing gear lever is in the UP position. When you push the gear lever down, the first thing to disengage are the mechanical locks, then the hydraulic pressure and the weight of the landing gears will let them deploy. The pressure system is designed so the door rams will close the doors again (to reduce drag), and at that point they're held in closed position just by the rams, the locks will not engage because the gear lever is down. Once you land pressure will bleed, and the doors will go down. In case of an emergency you can release the landing gear by pulling the emergency pressure release valve, but the landing gear will not manage to open the doors until the gear lever is also pushed down. This is also the reason why you have that extra strip of steel on the inside of the landing gear doors, so that the wheels can push the doors open without damaging them.
GOAT-ACEOFACES Posted February 24, 2014 Posted February 24, 2014 (edited) In order to ensure that the gear doors stay up and to avoid them opening in case of hydraulic pressure loss, there are mechanical locks that keep the doors shut when the landing gear lever is in the UP position. When you push the gear lever down, the first thing to disengage are the mechanical locks, then the hydraulic pressure and the weight of the landing gears will let them deploy. The pressure system is designed so the door rams will close the doors again (to reduce drag), and at that point they're held in closed position just by the rams, the locks will not engage because the gear lever is down. Once you land pressure will bleed, and the doors will go down. Agreed 100% This description agrees with the mustang pilot manuals (P51 - P82) too! And explains why, when the plane is landed and the gear are down that the cover fall/open when hydraulic pressure is removed, which some considered proof that they would fall/open even when the gear are up, which is clearly not the case and even a silly notion as your P51 owner/operator alluded to, i.e. would be silly to relay totally on hydraulic pressure to keep them closed, in light of the fact that hydraulic pressure can be lost! In case of an emergency you can release the landing gear by pulling the emergency pressure release valve, but the landing gear will not manage to open the doors until the gear lever is also pushed down. This is also the reason why you have that extra strip of steel on the inside of the landing gear doors, so that the wheels can push the doors open without damaging them.Ah, always wondered what that extra strip of metal was for in there! Thanks! Edited February 24, 2014 by ACEOFACES
Georgio Posted February 24, 2014 Posted February 24, 2014 I love it when there's a disagreement about small details as only then do you learn big details, thank you guys very informative... ^^
Sternjaeger Posted February 24, 2014 Posted February 24, 2014 Ah, always wondered what that extra strip of metal was for in there! Thanks! yeah, it puzzled me the first time I saw it too. If memory serves it was a field modification that was then introduced in production aircraft.
NZTyphoon Posted February 24, 2014 Posted February 24, 2014 I did, someone that owns and maintains Mustangs. I will go through the procedure again, perhaps this will help: The landing gear on the P-51 is hydraulically actuated, and so are the clam doors and tailwheel. They all respond to the same hydraulic system, as specified in the diagram posted above. In order to ensure that the gear doors stay up and to avoid them opening in case of hydraulic pressure loss, there are mechanical locks that keep the doors shut when the landing gear lever is in the UP position. When you push the gear lever down, the first thing to disengage are the mechanical locks, then the hydraulic pressure and the weight of the landing gears will let them deploy. The pressure system is designed so the door rams will close the doors again (to reduce drag), and at that point they're held in closed position just by the rams, the locks will not engage because the gear lever is down. Once you land pressure will bleed, and the doors will go down. In case of an emergency you can release the landing gear by pulling the emergency pressure release valve, but the landing gear will not manage to open the doors until the gear lever is also pushed down. This is also the reason why you have that extra strip of steel on the inside of the landing gear doors, so that the wheels can push the doors open without damaging them. From the P-51D/K Maintanence & Erection Manual: The uplocks for the main fairing doors were mechanical - once the mechanical locks were released the doors were opened and closed hydraulically via valves which controlled the timing and sequence. [/url] 1
Sternjaeger Posted February 24, 2014 Posted February 24, 2014 I'm sure that Crump will now understand that he got the whole thing wrong...
MiloMorai Posted February 24, 2014 Posted February 24, 2014 I'm sure that Crump will now understand that he got the whole thing wrong... History says he won't admit that he got it wrong.
GOAT-ACEOFACES Posted February 24, 2014 Posted February 24, 2014 From the P-51D/K Maintanence & Erection Manual: The uplocks for the main fairing doors were mechanical - once the mechanical locks were released the doors were opened and closed hydraulically via valves which controlled the timing and sequence.That wraps things up nicely! Another P51 sucks myth put out of its misery using simple logic and facts!
Crump Posted February 24, 2014 Posted February 24, 2014 There is a big difference between the early P-51 landing gear and the P-51D. The biggest difference is in the up-locks and the inner gear door system. The reason for the change was on the early D models, several airplanes crashed because the clam shell opened slightly in flight because the gear leg was tapping on it. At high speed, it would open slightly, the slip stream would catch it, rip it open and the wind would catch the exposed gear and wrench it out of the wing, causing the wing to be ripped off. When they designed the changes to make the -D they focused on lightening the airframe. They attempted to make the latches on the inner door hold the main landing gear up. This eliminated all the uplock linkage as seen in Princess. It didn't work as advertised and blame for some inflight breakups went to partial extension of the MLG. NAA then added uplocks for the gear leg to the -D. It was a much simpler design and as I install these parts into Enchantress I will try to get some pics. A hook was hung from each lower longeron. It has a spring and a direct linkage to the gear handle bellcrank on the R/H side of the cockpit. There are 3 push rods and 2 bellcranks (1 on each side) on the cockpit floor at the firewall that make up the linkage. Actually the hooks go opposite each other. 1 forward and 1 aft so a torque tube wouldn't work. http://www.warbirdinformationexchange.org/phpBB3/viewtopic.php?f=3&t=22220&sid=0476427ee7e632058bd7123cfbe3f488 Experience counts folks......
GOAT-ACEOFACES Posted February 24, 2014 Posted February 24, 2014 Experience counts folks......Agreed 100% Thank goodness Sternjaeger knows someone who actually owns and operates a P51, otherwise this myth may have continued.
GOAT-ACEOFACES Posted February 24, 2014 Posted February 24, 2014 Experience counts folks......Agreed 100% But.. you should have read the 2nd page, where the guy you quoted here (51fixer) said the following with regards to the main landing gear (MLG) The landing gear has devices to lock the gear in the up and down positions. On the MLG the down lock is spring operated to latch down and hyd to release. The uplock is spring operated to latch up and mechanical to release. The movement of the gear leg and the inner door are by hyd actuators. To control how the gear is synchronized there are valves and plungers with cable and linkages. In essence the timing of the operation of the components is important. With the gear up in flight the MLG is locked up by a hook and the inner door is shut and also locked by 2 hooks. By selecting gear down the latches on the inner door release and the uplock hook is released. This is by mechanical linkage which also moves the gear selector valve to provide hyd pressure from the up system to the down system. Hope this clears up the myth that MLG and doors will open up when hydraulic presser is lost
Sternjaeger Posted February 24, 2014 Posted February 24, 2014 (edited) http://www.warbirdinformationexchange.org/phpBB3/viewtopic.php?f=3&t=22220&sid=0476427ee7e632058bd7123cfbe3f488 Experience counts folks...... exactly, so perhaps it's time for some humble pie? I find it disarming that even when you're faced with facts and professionals' advice you still stubbornly stand by your wrong convictions. I mean, to be completely honest, your arrogant and condescending attitude is really your problem, even if I personally think it's something you should address (cos if you really fly and maintain aircraft as you say, this is gonna kill you or someone else some day..). But if you come here and start spreading false information in an arrogant manner just for the sake of showing off, then I'm afraid you might find people here that are actually knowledgeable and that will prove you wrong, as it has happened in several occasions before. I know this might come across as aggressive, and I apologise in advance, it was not my intention, it just really winds me up when people behave like you do, both on forums and real life. Edited February 24, 2014 by Sternjaeger
Rama Posted February 24, 2014 Posted February 24, 2014 Apparently, everything has been said on the subject. Time to lock
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